Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2013

The components of inventories are as follows (dollars in thousands):



	December 31
	2013			2012
Raw materials	$	212,027		$	125,909
Work in process	13,898			8,287
Finished goods	209,972			78,788
Supplies and materials	158,394			119,284
Inventories at FIFO or average cost	594,291			332,268
Excess of FIFO or average cost over LIFO cost	(71,768		)	(63,501		)
Inventories	$	522,523		$	268,767

Property, Plant and Equipment (at cost)

Property, plant, and equipment consist of the following (dollars in thousands):



	December 31
	2013			2012
Land and land improvements	$	140,592		$	107,250
Buildings	628,948			390,363
Machinery and equipment	4,263,505			3,048,932
Construction in progress	168,808			67,051
Other	30,847			27,196
Property, plant and equipment, at cost	5,232,700			3,640,792
Less accumulated depreciation	(2,426,996		)	(2,274,723		)
Property, plant, and equipment, net	$	2,805,704		$	1,366,069

Property, Plant and Equipment Estimated Useful Lives

Depreciation is computed on the straight-line basis over the estimated useful lives of the related assets. Assets under capital leases are depreciated on the straight-line method over the term of the lease or the useful life, if shorter. The following lives are used for the various categories of assets:



Buildings and land improvements	5 to 40 years
Machinery and equipment	3 to 25 years
Trucks and automobiles	3 to 10 years
Furniture and fixtures	3 to 20 years
Computers and hardware	3 to 10 years
	Period of the lease or
Leasehold improvements	useful life, if shorter